Poly(3,4-ethylenedioxythiophene)/carbon-based nanocomposite for gas sensing

Abstract

In this study, we have manufactured sensory films based on poly(3,4-ethylenedioxythiophene)/carbon nanotubes/reduced graphene oxide nanocomposite. The charge transport in obtained films was analyzed using impedance spectroscopy and temperature dependence of conductivity in the 90–325?K temperature range. The activation mechanism of charge transfer was established and the activation energy of conductivity was determined. The percolation effect in the nanocomposite was found with increasing the content of carbon nanoparticles. A decrease in resistance and an increase in the capacity of hybrid films due to the adsorption of water and ammonia molecules were revealed. Found features of the charge transport processes can expand the prospects of application of nanocomposite films for sensor electronics.     

Photosensitive Structures of Conjugated Polymer - Porous Silicon

The photosensitive hybrid structures poly-3,4-ethylenedioxythiophene (PEDOT)– porous silicon (PS)–n-Si are fabricated. Current-voltage characteristics of the obtained structures are investigated. It is shown that PS surface modification by PEDOT conjugated polymer gives rise to the appearance of a pronounced rectifying effect on the current-voltage characteristics. Spectral characteristics of photoresponse in the 450–1100 nm wavelength range, its temperature dependence in the 125–325 K range, and energy characteristics of the hybrid photovoltaic structures are studied. We propose possible mechanisms of the photoelectric processes in the hybrid structures PEDOT–PS–n-Si.     

Electrical and sensory properties of zinc oxide – porous silicon nanosystems

Abstract

Zinc oxide nanostructures have been grown by electrochemical deposition on porous silicon–silicon substrate. The photoelectric and sensory properties of the obtained ZnO–porous silicon nanosystems were investigated in both DC and AC regimes. The obtained structures were characterized by photosensitivity in the 400–1100?nm wavelength range and by high sensitivity to moisture. Increase of relative humidity resulted in significant decrease of the electrical resistance and increase of the capacitance of the hybrid structures. To estimate the sensory properties of the ZnO–porous silicon nanostructures their adsorption sensitivity and dynamic characteristics were analyzed. Discovered features of the charge transport processes broaden the prospects of the semiconductor nanosystems application in gas sensors and photodetectors.     

Structure of natural film on porous silicon surface founded by ellipsometry

Abstract

The multiple-angle-of-incidence ellipsometric studies of the natural film formed on the surface of porous silicon sample after its production and subsequent keeping in isopropyl alcohol have been performed. A new property of porous silicon with the natural film on its surface has been revealed which consists in a drastic change of the polarization characteristics of the reflected light wave after its keeping in alcohol. This property of porous silicon may be the basis for the development of liquid and gas sensors, polarization elements of optical devices etc. It was found that ellipsometric curves are described better by calculations in a two-layer model in comparison with a single-layer one of the investigated film. It was obtained that the outer layer of the film has smaller refractive index than the inner one. As a result of decoration the refractive indices of both layers decrease and further the changes of refractive indices and the redistribution of the thickness of both layers are found. It is suggested that the interaction of the alcohol molecules with silicon and its oxide environment occurs in the walls of the pores during the decoration.     

Photoacoustic studies on optical and thermal properties of p‐type and n‐type nanostructured porous silicon for (100) and (111) orientations

Nanostructured p‐type and n‐type porous silicon samples were prepared for (100) and (111) orientations and a systematic study is carried out on the effects of orientations, dopant type (boron and phosphorous), current density (20 and 30mA/cm²) and etching time on the formation, optical and thermal properties by photoacoustic spectroscopy. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis of a two‐dimensional porous framework based on symmetrical organic ligand and linking metal ion

Reaction of a pyridinecarboxylate ligand with copper salt affords a novel coordinative polymer [Cu(bpdc)(H₂O)₂·2H₂O]n (bpdc=.2,2'‐bipyridyl‐3,3'‐dicarboxylate). It has 2‐D (4,4) layered network extended by the tetradentate bridging ligands, further interestingly, the coordinative and lattice water molecules acting as donor and acceptor linking the uncoordinated carboxylate groups into a inorganic (6,3) network. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

多孔硅-Au/Ag枝晶复合材料研究进展

基于金属包裹的多孔硅衬底具有制备成本低、检测能力强的优点.自20世纪表面增强拉曼散射(SERS)现象被发现以来,多孔硅-Au/Ag复合材料逐渐展现出作为SERS衬底的优势,被广泛应用于生物、化学、医疗等领域.本文综述了近些年来基于多孔硅复合Au/Ag纳米颗粒混合平台的研究,重点讨论了将贵金属Ag/Au复合于多孔硅衬底上...     

Synthesis of high purity calcium carbonate micro‐ and nano‐structures on polyethylene glycol templates using dolomite

This research paper describes the synthesis of nano‐ and micro‐structures of high purity precipitated calcium carbonate (PCC) on poly(ethylene glycol)(PEG) templates for broad‐range industrial applications, using readily available and cheap impure dolomitic marbles. In the method, calcium components of impure dolomitic marbles are extracted as calcium sucrate which is then bubbled with carbon dioxide gas using a carbonation column in the presence of PEG. The effects of concentration of PEG, pH of calcium sucrate solution and temperature on the final yield, morphology and polymorphism of PCC have been studied. Vaterite and calcite are the crystalline forms of calcium carbonate found in final PCC products. The vaterite is observed as hollow spheres with particle diameter of 1.5‐2 μm which is formed by aggregation of vaterite nanoparticles with particle size of 20 nm on PEG templates. Optimum conditions for the highest PCC yield of 79.94% are 0.4 mol dm⁻³ of PEG, pH of 6.5 and temperature of 80 °C. The purity of PCC products is about 99%. Therefore, the synthesized PCC products are of required purity and quality for industrial applications.     

基于POLO钝化接触结构的晶硅电池技术及其研究进展

多晶硅氧化物(POLO)结构是在晶硅表面依次生长一层极薄的界面氧化层与多晶硅层所形成的钝化接触结构。基于POLO结构的钝化接触技术不仅能够获得优异的表面钝化特性,而且避免了金属与晶硅表面的直接接触,极大地降低了金属与晶硅表面的接触复合。目前应用POLO钝化接触结构制作的小面积晶硅太阳能电池转换效率高达26.1%,制作的大面积晶硅太阳能电池产业化效率已经超过24.5%。同时POLO钝化接触技术应用于晶硅电池的制作可以承受高温工艺,兼容现有的晶硅电池产业化设备,是未来极具产业化潜力的钝化接触技术方案。本文主要综述了POLO钝化接触结构中载流子的传输机理及相应的量化参数表征方法;对比了POLO结构制备中界面氧化层生长、多晶硅层的沉积、掺杂及氢化处理的方法;总结了多晶硅层的寄生吸收效应、晶硅表面形貌结构、掺杂浓度分布对POLO结构钝化接触特性的影响;简述了POLO钝化接触技术的研究进展及当前POLO电池制作面临的技术难点。     

A novel stable CuI complex based on an unconjugated bisanthryl-tethered diimine ligand with tri-coordinate mode

The first air-stable mononuclear Cu^I complex (1) based on an unconjugated bisanthryl-tethered diimine ligand has been synthesized and characterized by elemental analysis, ESI-MS, UV-vis, FT-IR spectra and TGA analysis. X-ray diffraction analysis at room temperature reveals that complex 1 crystallizes in a monoclinic system, space group P2₁/c with a=15.611(3) ?, b=24.412 (5) ?, c=15.430 (6) ?, β=114.49 (3)°, V=5351.3 (19) ?³, ρ _calc=1.359 g cm⁻³, μ=0.472 mm⁻¹ and Z=4. The crystal structure of 1 features a mononuclear tricoordinated complex with a distorted triagonal planar geometry. The Cu^I center is coordinated to three imine N atoms of two Schiff base ligands, while the remaining one imine N atom keeps uncoordinated. UV-vis absorption and emission spectra indicate that the complexation of metal ion has slight influence on the electronic structure of the ligand. TGA analysis confirms that complex 1 is stable up to 253°C.Supplementary materials Crystallographic data reported in this paper have been deposited with Cambridge Crystallographic Data center (CCDC no.282672). Copies of the data can be obtained free of charge from www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cambridge Crystallographic Data Center, 12, Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033; or deposit@ccdc. cam. ac.uk).     

Syntheses,crystal structures and properties of Cd(II) and Ag(I) complexes based on 2-p-methylphenyl-5-(2-pyridyl)-1,3,4-thiadiazole

Abstract

Complexes of [CdL₂(NO₃)₂]·1.5H₂O and [Ag₂(μ-L)₂(NO₃)₂] were synthesized by the reactions of 2-p-methylphenyl-5-(2-pyridyl)-1,3,4-thiadiazole (L) with Cd(NO₃)₂·4H₂O and AgNO₃, respectively. Their structures were determined by single crystal X-ray diffraction. The photophysical property and thermal stability were characterized by FT???IR, UV???Vis absorption, fluorescence, and thermogravimetric analysis (TGA). Both complexes belong to the triclinic system with space group p???1. The central metal of [CdL₂(NO₃)₂]·1.5H₂O has a distorted octahedral geometry [CdN₄O₂], while two central Ag(I) atoms of [Ag₂(μ-L)₂(NO₃)₂] exhibit distorted tetrahedral geometries [AgN₃O].     

B掺杂量对LPCVD生长大面积ZnO透明导电薄膜性能的影响

采用低压化学气相沉积(LPCVD)技术在大面积的玻璃衬底上制备了B掺杂ZnO(BZO)透明导电薄膜,研究了不同B2H6掺杂量对BZO薄膜微观形貌、导电能力及其均匀性、透光率等性能的影响.结果表明,所制备的BZO薄膜表面具有自生长的绒面结构;B2H6掺杂量由30 sccm增加到60 sccm,BZO薄膜的方阻由28.6Ω/□减小到14.1 Ω/□,导电能力显著增强,同时方阻均匀性也明显提升;BZO薄膜在长波区的透光率随B2H6掺杂量的增加而明显降低,综合透光率结果,最佳B2H6掺杂量控制在60～ 90 sccm之间.